A process for advantageously producing a graphene/SiC composite material is provided in which a large-area graphene layer that is flat in an atomic level is formed on a SiC single crystal substrate. The process for producing a graphene/SiC composite material in which at least one graphene layer is formed on a SiC single crystal substrate, comprising the steps of: removing an oxide film that is formed by natural oxidation and covers a surface of the SIC single crystal substrate, thereby exposing a Si surface of the SiC single crystal substrate, heating the SiC single crystal substrate with the Si surface exposed under an oxygen atmosphere, thereby forming a SiO2 layer on the surface of the SiC single crystal substrate, and heating the SiC single crystal substrate under vacuum on which the SiO2 layer was formed.